基于IPv6的下一代网络在校园网中的实现

本文简要介绍了下一代互联网的发展,研究了从IPv4到IPv6的过渡方式,包括双协议栈技术、隧道技术以及网络地址转换／协议转换技术;重点解决了以下几个问题：①通过在校园网出口增加双栈交换路由设备并使用双栈技术,实现了一条线路同时连接CERNET-9CERNET2网络;②在校内核心交换机上建立ISATAP隧道入口,使校内用户可以通过隧道方式访问CERNET2资源;③在UNIX系统上使用Bind9搭建了基于IPv6协议的域名系统,能同时为IPv4和IPv6网络解析校内IPv6域名。目前,重庆师范大学IPv6网络的基础结构和基础应用服务已经构建完毕,为以后从IPv4网络向IPv6网络过渡做准备,也为没有构建IPv6校园网的学校提供参考。     

三峡水库蓄水后澎溪河消落带植物群落格局及多样性

三峡水库156m蓄水后,消落带内植物种类组成、空间分布格局以及多样性发生巨大变化。2008年7～9月对开县澎溪河及支流自夹溪沿岸海拔175m以下范围的植被进行调查：在澎溪河设置3个样带,在白夹溪设置2个样带,共108个草本样方。结果表明：共发现98种维管植物,分属于38科29属,其中水生、湿生植物52种;一年生植物和隐芽植物种类丰富,分别占52．0％和31．6％;调查区域内植被可划分为11个群丛;沿河流侧向空间梯度可分为河漫滩一年生草本植物带、苍耳带、双穗雀稗带、白茅带4个植物带;土壤含水率的变化及分布格局对消落带植物带状分布有较大影响。研究表明消落带内植物物种丰富度和多样性较低。     

基于Curvelet变换的图像去噪

小波变换在分析二维图像中曲线或者直线边缘特征方面存在明显不足,而由小波变换而来的Curvelet变换具有很强的方向性,能更好地逼近和稀疏表达平滑区域和边缘部分。本文首先介绍了一代和二代Curvelet变换的概念及二代Curvelet变换快速离散算法的实现,然后分别采用小波变换和二代Curvelet变换的快速离散算法进行图像去噪实验。实验采用Wrap（Wrapping—based transform）算法实现有关Curvelet变换,即在USFFT方法上增加一个Wrap步骤,将任意区域通过周期化技术一一映射到原点的仿射区域。对比试验结果表明,在图像消噪中二代Curvelet变换的离散算法较小波变换有更好的视觉效果,而且PSNR也有一定的提高。     

The FN3 and BRCT motifs in the exomer component Chs5p define a conserved module that is necessary and sufficient for its function

Chs5p is a component of the exomer, a coat complex required to transport the chitin synthase Chs3p from the trans-Golgi network to the plasma membrane. The Chs5p N-terminal region exhibits fibronectin type III (FN3) and BRCT domains. FN3 domains are present in proteins that mediate adhesion processes, whereas BRCT domains are involved in DNA repair. Several fungi—including Schizosaccharomyces pombe, which has no detectable amounts of chitin—have proteins similar to Chs5p. Here we show that the FN3 and BRCT motifs in Chs5p behave as a module that is necessary and sufficient for Chs5p localization and for cargo delivery. The N-terminal regions of S. cerevisiae Chs5p and S. pombe Cfr1p are interchangeable in terms of Golgi localization, but not in terms of exomer assembly, showing that the conserved function of this module is protein retention in this organelle and that the interaction between the exomer components is organism-specific.     

Cytolytic and K+ channel blocking activities of β-KTx and scorpine-like peptides purified from scorpion venoms

Among the scorpion venom components whose function are poorly known or even show contrasting pharmacological results are those called “orphan peptides”. The most widely distributed are named β-KTx or scorpine-like peptides. They contain three disulfide bridges with two recognizable domains: a freely moving N-terminal amino acid sequence and a tightly folded C-terminal region with a cysteine-stabilized α/β (CS-αβ) motif. Four such peptides and three cloned genes are reported here. They were assayed for their cytolytic, antimicrobial and K ⁺ channel-blocking activities. Two main characteristics were found: the existence of an unusual structural and functional diversity, whereby the full-length peptide can lyse cells or kill microorganisms, and a C-terminal domain containing the CS-αβ motif that can block K ⁺ channels. Furthermore, sequence analyses and phylogenetic reconstructions are used to discuss the evolution of this type of peptide and to highlight the versatility of the CS-αβ structures. Received 13 August 2007; received after revision 30 October 2007; accepted 2 November 2007     

应用型本科高校计算机类专业学生创新实践能力的培养——基于“恩智浦”杯智能车竞赛

针对应用型本科高校计算机类专业学生创新实践能力的培养，提出了一种以全国大学生“恩智浦”杯智能车竞赛为载体，分4个阶段逐步培养学生创新能力的培养体系。经过9 a多的努力，形成了良好的培养流程，学生获得优秀竞赛成绩、对口就业率提高。     

Reconstructing Native American population history

The peopling of the Americas has been the subject of extensive genetic, archaeological and linguistic research; however, central questions remain unresolved. One contentious issue is whether the settlement occurred by means of a single migration or multiple streams of migration from Siberia. The pattern of dispersals within the Americas is also poorly understood. To address these questions at a higher resolution than was previously possible, we assembled data from 52 Native American and 17 Siberian groups genotyped at 364,470 single nucleotide polymorphisms. Here we show that Native Americans descend from at least three streams of Asian gene flow. Most descend entirely from a single ancestral population that we call 'First American'. However, speakers of Eskimo-Aleut languages from the Arctic inherit almost half their ancestry from a second stream of Asian gene flow, and the Na-Dene-speaking Chipewyan from Canada inherit roughly one-tenth of their ancestry from a third stream. We show that the initial peopling followed a southward expansion facilitated by the coast, with sequential population splits and little gene flow after divergence, especially in South America. A major exception is in Chibchan speakers on both sides of the Panama isthmus, who have ancestry from both North and South America.     

Preface

正All-optical implementations of signal processing have attracted a great deal of attention due to the unique potential of this approach to overcome the bandwidth and speed bottleneck of electronic devices.Many all-optical signal processing techniques,offering processing bandwidths up to several THz,have been proposed and successfully employed in a wide range of areas,such as     

基于丝网印刷技术的电化学酶联免疫吸附

为研究基于丝网印刷技术的电化学酶联免疫吸附(ELISA)的效果,在塑料基板上印刷96孔电极单元,形成标准96孔ELISA检测板,建立电化学检测与ELISA实验的关联,检测板每孔底部为独立电化学单元,由碳电极、对电极和银参比电极组成,形成双面印刷基板,基板通过96×3针式镀金特定连接器连接至恒电位仪。结果表明,96孔三电极电化学丝网印刷电化学阵列作为ELISA检测是可行的,多通道恒电位仪可同时测量8个孔数据。     

用混合遗传算法求解物流配送路径优化问题

为了改善物流配送路径优化问题的运算质量,提出一种将遗传算法和模拟退火算法相结合的混合遗传算法。通过仿真 实例验证,证明混合遗传算法的解优于单纯使用遗传算法和模拟退火算法所得到的解,同时混合遗传算法与传统优化算法相 比收敛速度更快,分配结果更优良,具有很好的应用价值。